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NS-3 supports three rate-adaptation algorithm Which works with IEEE standard 802.11c, namely
- ConstantRate
- MinstrelHt
- Ideal
Implementation of Each of them can be found in ns-3/modules/...
- ns3::ConstantRateWifiManager - use constant rates for data and RTS transmissions. This class always uses the same transmission rate for every packet sent.
- ns3::IdealWifiManager - This class implements an 'ideal' rate control algorithm similar to RBAR in spirit (see A rate-adaptive MAC protocol for multihop wireless networks by G.
- ns3::MinstrelHtWifiManager - Minstrel-HT is a rate adaptation mechanism for the 802.11n/ac standard based on Minstrel, and is based on the approach of probing the channel to dynamically learn about working rates that can be supported
For the comparison these Rate Adaptation Algorithms, We have used topology from the below paper.
Reference Paper : A comparative simulation study of rate adaptation algorithms in wireless LANs
The above figure shows the topology we used for the comparison of the RAAs which we created by modifying the file “ examples/tutorials/third.cc” in ns-3. The topology contains 10 wired LAN nodes connected to each other and one of the nodes is connected to the stationary Access Point(AP) of the Wireless Network using a point to point link with 50Mbps bandwidth and 10ms delay.
| Error Rate Model | NistErrorRateModel |
|---|---|
| Channel Delay Model | ConstantSpeedPropagationDelayModel |
| Channel Loss Model | LogDistancePropagationLossModel |
| MAC(Station/AP) Type | Sta WifiMac/ ApWifiMac |
| Application Data Rate | 1 Mbps |
| Packet Size | 1024 bytes |
| Number of nodes | 10/24 Nodes |
| Mobility Model | RandomDirectional2dMobilityModel |
| Mobility Speed | Random Variable : U(15.0 mps, 20.0 mps) |
| Simulation Topology of Wifi nodes | Grid, rectangle range: (-100m, 100m, -100m, 100m) |
We have simulated this topology with three different RAAs (Ideal, Constant & MinstrelHT) And No. of STAs from 3 to 12. From, Those simulations we got values of average Throughput and average Delay which can be seen in the below Images.
For all the experiments we have plotted Throughput vs Time And Delay vs Time graphs. Which can be seen as GIF below,
- The performance of Ideal RAA was better than the other two in each and every case.
- The throughput and delay of Ideal RAA had the least fluctuations observed.
- MinstrelHt RAA gets the second best throughput exceeding the performance of ConstantRate manifold but fluctuations in throughput are very starc.
- The delay of MinstrelHt comes very close to Ideal RAA in almost every case.